Abstract
The effect of the heat treatment, which was applied under various conditions, on δ-aminolevulinic acid dehydrase (ALAD) activities was investigated by means of determination of ALAD activities in the peripheral blood of normal rabbits (N-rabbit) and intravenously lead-injected rabbits (Pb-rabbit). Furthermore, lead was added in vitro to N- or Pb-rabbits' blood, then ALAD activities were assayed with and without heat treatment. The following findings were obtained:
(1) ALAD activity of the N-rabbit blood decreased monotonously with increase of temperature and time of the heat treatment. (2) Decrease of ALAD activity of the Pb-rabbit blood is shown in Table 1. (3) In both N- and Pb-rabbits' blood, the ALAD activities after heat treatment at 60°C for 5min converge to a definite value, which is about 1/3 of ALAD activity of the N-rabbit blood, the value being nearly constant and independent of the doses of lead administration. It was revealed that an increase of the activity by the heat treatment in the Pb-rabbit blood takes place only in cases in which the initial activity is lower than this value. (4) When lead was added to the N- or Pb-rabbit blood in vitro, (a) ALAD activity was not affected by 2.9×10-10M Pb concentration in incubation mixture in both cases. (b) By 2.9×10-8M Pb ALAD activity fell to about 50% in the N-rabbit blood and to 40∼20% in the Pb-rabbit blood, the latter depending upon the doses of lead previously administered in vivo. (c) Decrease of ALAD activity by heat treatment was enhanced by adding lead in vitro, and this effect was more remarkable in the rabbit blood which was affected by previous administration of lead. (5) Preincubation of the N- or Pb-rabbit blood with lead only enhanced the decrease of ALAD activity, without showing any increase in the activity.
